Calorimetric data of primary crystallization is usually interpreted in the framework of the
Kolmogorov Dokl. Akad. Nauk SSSR 1, 355 1937 , Johnson and Mehl Trans. AIME 135, 416
1939 , and Avrami J. Chem. Phys. 7, 1103 1939 ; 8, 212 1940 ; 9, 177 1941 KJMA theory.
However, while the KJMA theory assumes random nucleation and exhaustion of space by direct
impingement, primary crystallization is usually driven by diffusion-controlled growth with soft
impingement between the growing crystallites. This results in a stop of the growth before the space
is fully crystallized and induces nonrandom nucleation. In this work, phase-field simulations are
used to check the validity of different kinetic models for describing primary crystallization kinetics.
The results show that KJMA theory provides a good approximation to the soft-impingement and
nonrandom nucleation effects. Moreover, these effects are not responsible of the slowing down of
the kinetics found experimentally in the primary crystallization of glasses.